GRID-Arendal : State of the Environment Norway - Climate change

Climate change

Man made greenhouse gases

Greenhouse gases. Approximate values.

GWP - Global Warming Potential - describes the relative importance of different greenhouse gases in comparison to CO2. The GWP is described as CO2-equivalents. (Measuring the GWP of greenhouse gases, IUCC; UNEP, Geneva)
• Carbon dioxide (CO2), released by nearly all forms of life through their metabolism, is fundamental to life. During daytime, the carbon in the gas is assimilated in the photosynthesis in green plants to build up sugars. In this process oxygen is released into the atmosphere. Without this natural process, life as we know it could not exist.

  In addition to this natural carbon cycle, Carbon dioxide is emitted through the burning of fossil fuels: coal, oil and oil-products such as petrol and gas. Putrefying organic materials and the burning of wood, paper and other organic matter also emit CO2. In stationary combustion, gas, heating oils and kerosene are forms of energy sources emitting CO2. These emissions fluctuate with temperature variations. The colder the weather, the more heating is needed. If sufficient hydroelectricity is not available, the burning of fossil fuels will increase.

  Water vapour and CO2 are the major natural greenhouse gases of the atmosphere. Water vapour is the most important green house gas. However, this gas will not be treated further here, as water vapour is not anthropogenic; human activities have little or no impact on the amount in the atmosphere.
  The CO2-concentration in the atmosphere has increased from 280 parts per million by volume (ppmv) to 358 ppmv or 0.036 per cent CO2 in 1994. This gives a general increase of over 27 per cent since preindustrial times. With an increase of CO2, it is likely that the storing capacity of energy in the atmosphere will be affected.

  Of the total global man-made emissions of CO2 , Norway released approximately 41 million tonnes, or approximately 0.2 per cent in 1996. Per capita this is rather high, just above 9 tonnes of CO2. Global average is approximately 3.9 tonnes per capita. In 1989 the CO2 emissions per capita in Norway were 8,3 tonnes, which is the Norwegian aim for the year 2000.

  Burning of wood is not considered as contributing to the greenhouse effect, since the energy released is assumed to be balanced by new tree growth.

  The global yearly increase of CO2 in the atmosphere is now appr. 0.5 per cent.

• Methane (CH4) is discharged from gas- and oilfields, rice paddies and from organic material decaying without oxygen, e.g. in swamps, marshes and large garbage dumps. Methane is also discharged from the stomachs of mammals, especially cattle. The largest deposits of methane are found in the vast frozen marshes of the Siberian tundra.
  The CH4 in the atmosphere has increased 145 per cent since preindustrial times.This increase has been linked to the rapid world population growth resulting in demands for energy, food, water, shelter and other basic needs.
  Norwegian emissions of methane were approximately 471,000 tonnes in 1996. The emissions increased by 10 per cent from 1989 to 1996.

  Norwegian emissions mainly come from livestock (21%) and decomposition of waste in landfills .-Emissions from landfills account for almost 70 per cent. The number of landfills is now decreasing, and at some landfills, the methane gas is now collected.In spite of this, methane emissions increase due to increasing depositions of organic waste.

  Methane has a GWP of 21 times that of CO2.

• Nitrous oxide (N2O), also referred to as laughing gas, comes from artificial fertilizers used in farming and from the burning of fossil fuels. Concentrations of nitrous oxide have grown by 15 per cent since pre-industrial times. Emission figures for N2O are difficult to estimate, and therefore rather uncertain. Norwegian emissions were estimated to be 14,2 thousand tonnes in 1995. Almost half of the Norwegian emissions come from fertilizers in the agricultural sector. Production of nitric acid is another important source of emissions of N2O. Emissions of N2O has decreased by 7 per cent since 1989 due to a decrease in the production of nitric acid. This gas has a GWP of 310 times that of CO2.

• Fluorine-containing gases as HFC, CF4, C2F6 and SF6 have GWPs ranging from 140 to 23900.

CO2-equivalents.
Due to the decrease of emissions of fluorine-containing gases, the total emissions of CO2-equivalents in Norway has remained rather stable, and has been fluctuating between 50 and 55 million tonnes per year since 1989. (54 million tonnes in 1989, 55 million tonnes in 1994)

Time lag

Some greenhouse gases remain in the atmosphere for decades and even centuries at a time. Consequently, the planet may continue to warm, even if we stopped producing all man-made emissions at once. The effect of this global warming on sea level rise and other ecosystem changes could be dramatic.